The present invention relates to seat technology, and, more particularly, to seat technology used in vehicles which undergo severe vibration and vehicles which may be involved in one or many high impact events wherein the seat is designed in part to minimize injury to the occupant.
Situations exist where vehicle occupants are exposed to excessively high levels of whole body shock and vibration that, at a minimum, can be uncomfortable and, in extreme cases, can result in serious bodily injuries. With regard to vehicles, this can include, but is not limited to:                Vehicles that travel off road over very rough terrains at low and high vehicle speeds;        Material handling vehicles, such as fork lifts, that have to travel over speed or other types of bumps or rough roads or terrains;        Above-ground and underground mining vehicles that travel over rough roads and underground terrains;        Boats that travel at high speeds in very rough seas and other rough waters;        Vehicles that are exposed to explosive devices, such as land minds and improvised explosive devices (IED's), and        Train locomotives during the coupling and uncoupling of train cars.        
Bodily injuries can sometimes be experienced as a result of a major single shock or vibration event of extremely high level or as a result of successive exposures over a long period of time to shock and vibration events of moderate or high levels. Vehicle occupants who have sustained previous back injuries from other causes may be much more sensitive and even intolerant to even moderate levels of whole body shock and vibration exposures from the operation of vehicles. The Parliament of the European Union (EU) has enacted its Human Vibration Directive to limit the exposure levels of vehicle operators and occupants in member countries of the EU to whole body shock and vibration.
Much has already been done to protect over-the-road and off-road vehicle operators from exposure to whole body shock and vibration. One of the main advances has been in the design, development and continued improvements of air-ride seat systems. Air-ride seat systems are often used in commercial long-haul tractor-trailer rigs and heavy constructions vehicles, such as, dozers, tractor-scrapers and large off-road dump trucks. The air-ride seat system is designed to attenuate low-to-moderately-high frequency continuous vibration and moderate shock levels to which vehicle operators are exposed. It accomplishes this with a low resonance frequency seat isolation system that is supported by a pneumatic spring and an associated damping element. Some air-ride seat systems may passively respond to shock and vibration inputs, and others may be controlled by an active or semi-active vibration control system. While there are several major advantages to such air-ride seat systems, there are significant disadvantages:                They are expensive.        Vehicle exposures to sudden large shock inputs often result in large vertical displacements of the seat and seat occupant. This can result in the seat occupant experiencing uncomfortable severe jolts when the seat hits its motion limits or in the seat occupant hitting his/her head on the vehicle cab roof.        Many air-ride seat systems require a large amount of clear vertical space within a vehicle cab to work effectively.        Most air-ride seat systems give the seat occupant protection for whole-body shock and vibration exposure only in the vertical direction. They do not afford protection in the horizontal (front-to-back) direction.        
There are many situations where air-ride shock and vibration isolation seat systems will not work effectively. These include vehicles that:                Have vehicle operator and occupant compartments with very limited vertical clear space;        Are exposed to single or repetitive high shock inputs;        Are exposed to single excessively high shock inputs, and        Need operator shock and vibration attenuation in both the vertical and horizontal directions.        
Material handling vehicles, underground mining vehicles, high-speed off road vehicles, some high-speed boats, military and non-military vehicles that can be exposed to land mines and IED's, and train locomotives all fall into one or more of the above categories.
Air bladder systems have long been used for seat cushions and air mattresses and in wheel chair, bicycle, motor cycle, and vehicle seats. They have also been used in hospital beds and beds used in ordinary homes. With the exception of bicycle and motorcycle seats, air bladder systems have primarily been used in seat cushions, air mattresses, wheel chair seats and vehicle seats to improve comfort. Air bladder seat systems used on bicycles and motor cycles have been designed to attenuate low level vibration and shock directed into the buttock of bicycle and motor cycle riders. However, bicycle and motor cycle air bladder seat systems were primarily designed to improve ride comfort. None of these systems were designed to protect individuals from high-level single or multiple shocks. Improvements can be made in effectively using air bladder designs in seat technology for vehicles which undergo severe vibration and vehicles which may be involved in one or many high impact events.